26 BULLETIN 1365 ; U. S. DEPAKTMENT OE AGKICULTUKE 
shedding of squares from the main stalks and vegetative limbs com- 
bined was 47 per cent for Pima and 51 per cent for Acala. 
In 1924 the 20 Pima plants, none of which had vegetative limbs, 
developed 50 per cent of their squares into mature bolls; the Acala 
plants with the main stalks and vegetative limbs combined developed 
only 11 per cent. In 1925, combining the data from main stalks 
and vegetative limbs of the Pima and of the Acala, the percentage 
of squares developing into mature bolls was 46 and 16 for the 
respective varieties. 
The mean age at which Pima squares shed was the fourteenth day 
after appearance in 1924 and the seventeenth day in 1925. The 
mean age at which Acala squares shed was the fifteenth day in 1924 
and the eighteenth day in 1925. More Acala squares shed when well 
advanced in age than in the case of the Pima, and the period in the 
development of a square in which it was likely to shed was longer 
for the Acala in both seasons. 
Among squares of the same date those on the outer nodes of the 
fruiting branches of both varieties required longer periods to develop 
into flowers than those on the inner nodes, closer to the main axis 
of the plant. Also there was a lengthening of the periods on all of 
the nodes as the season progressed, though squares on second nodes 
usually developed more rapidly than those on the first or third nodes. 
The mean square period for Pima was slightly over 33 days in both 
seasons, and for Acala the period was 28 days in 1924 and 29 days 
in 1925. 
On specific nodes of fruiting branches of both varieties the per- 
centage of square shedding increased and the percentage of squares 
developing into bolls decreased toward the ends of the branches. 
Branches of one node only, both on the main stalks and on the 
vegetative limbs of both varieties, had a higher percentage of squares 
shed and a lower percentage of squares developing to mature bolls 
than on node 1 of longer fruiting branches. The last or outer node 
of all fruiting branches of two or more nodes on the main stalks and 
vegetative limbs of each variety shed a larger proportion of squares 
and developed a smaller proportion to mature bolls. Boll shedding 
from specific nodes increased appreciably in both varieties on the 
outer nodes of the fruiting branches. 
The Pima and Acala squares were shed in shorter periods in the 
early part of the season than in the later. The position of a square 
on a fruiting branch of Pima did not materially hasten or retard the 
shedding of that square, as squares on inner nodes were not consist- 
ently shed earlier than those on the outer nodes. Squares which 
shed from the outer nodes of Acala branches were usually somewhat 
older than those which fell from the inner nodes. 
The maturation period of bolls of the same flowering date was 
longer on the outer than on the inner nodes of the fruiting branches 
of both varieties. Boll periods on all nodes lengthened as the season 
progressed. The mean boll period for the season was about 58 days 
on Pima and about 53 days on Acala in 1924 and about 62 days on 
Pima and 57 days on Acala in 1925. 
The boll period on node 2 apparently was lengthened by the 
presence of a boll on node 1 . When node 1 bore no boll, the boll on 
the second node developed in as short a time as a boll on the first 
node would have required. 
